NeroEngine/Timing.cpp at master · nerososft/NeroEngine · GitHub

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#pragma once

#include "Timing.h"
#include <SDL\SDL.h>

namespace NeroEngine{

	FpsLimter::FpsLimter(){

	}

	void FpsLimter::init(float maxFPS){
		setMaxFps(maxFPS);
	}

	void FpsLimter::setMaxFps(float maxFPS){
		_maxFPS = maxFPS;
	}

	void FpsLimter::begin(){
		 _startTicks = SDL_GetTicks();
	}

	float FpsLimter::end(){
		calculateFPS();
		float frameTicks = SDL_GetTicks() - _startTicks;
		//ÏÞÖÆfps
		if (1000.0f / _maxFPS>frameTicks){
			SDL_Delay(1000.0f / _maxFPS - frameTicks);
		}

		return _fps;
	}

	void FpsLimter::calculateFPS(){

		static const int NUM_SAMPLES = 10;
		static float frameTimes[NUM_SAMPLES];
		static int currentFrame = 0;
		static float prevTicks = SDL_GetTicks();
		float currentTicks;
		currentTicks = SDL_GetTicks();

		_frameTime = currentTicks - prevTicks;
		frameTimes[currentFrame % NUM_SAMPLES] = _frameTime;

		prevTicks = currentTicks;
		int count;
		currentFrame++;
		if (currentFrame<NUM_SAMPLES){
			count = currentFrame;
		}
		else{
			count = NUM_SAMPLES;
		}

		float frameTimeAverage = 0;
		for (int i = 0; i < count; i++){
			frameTimeAverage += frameTimes[i];
		}
		frameTimeAverage /= count;

		if (frameTimeAverage>0){
			_fps = 1000.0f / frameTimeAverage;
		}
		else{
			_fps = 60.0f;
		}
	}

}